The present invention relates to a floating rotary drive device for a workpiece to be machined by grinding, of the type comprising a chuck securely attached, by a flexible control, to the output shaft of a motor and to means for positioning the said workpiece machining of which is completed.
In the machining by "plunge" grinding of some materials, particularly resilient or semi-resilient, it may be advantageous to give some slack to the workpiece in the course of machining and/or surfacing.
Such slack can be obtained only by a supple connection between motor and workpiece to be machined and this necessarily means variations in the relative positioning of the workpiece in the course of machining and of the drive device.
Now, although it is relatively simple to reposition rigorously, at rest, the workpiece machining of which is completed, for example with a device with springs coming to press the two ends of the shaft of the said workpiece against two stops having a definite position, the same is not true of the intermediate drive system between the motor device and the workpiece, even repositioned. In fact, at the moment of stopping, the position of this device remains random in the space where it has to move in order to permit the desired slack of the workpiece in the course of machining. Moreover, after release of the workpiece machining of which is completed, its supple connection with the motor does not even allow it to keep the same position.
The consequence is an absence of constant repetitive positions allowing an automation, by simple mechanization, of the operations of coupling with the new workpiece to be machined.
Moreover, it is plain that every workpiece must be coupled with this drive device so that it can be machined, and then released after machining.